1 menu "CPU Frequency scaling"
4 bool "CPU Frequency scaling"
6 CPU Frequency scaling allows you to change the clock speed of
7 CPUs on the fly. This is a nice method to save power, because
8 the lower the CPU clock speed, the less power the CPU consumes.
10 Note that this driver doesn't automatically change the CPU
11 clock speed, you need to either enable a dynamic cpufreq governor
12 (see below) after boot, or use a userspace tool.
14 For details, take a look at <file:Documentation/cpu-freq>.
23 config CPU_FREQ_GOV_COMMON
27 tristate "CPU frequency translation statistics"
31 This driver exports CPU frequency statistics information through sysfs
34 To compile this driver as a module, choose M here: the
35 module will be called cpufreq_stats.
39 config CPU_FREQ_STAT_DETAILS
40 bool "CPU frequency translation statistics details"
41 depends on CPU_FREQ_STAT
43 This will show detail CPU frequency translation table in sysfs file
49 prompt "Default CPUFreq governor"
50 default CPU_FREQ_DEFAULT_GOV_USERSPACE if CPU_FREQ_SA1100 || CPU_FREQ_SA1110
51 default CPU_FREQ_DEFAULT_GOV_PERFORMANCE
53 This option sets which CPUFreq governor shall be loaded at
54 startup. If in doubt, select 'performance'.
56 config CPU_FREQ_DEFAULT_GOV_PERFORMANCE
58 select CPU_FREQ_GOV_PERFORMANCE
60 Use the CPUFreq governor 'performance' as default. This sets
61 the frequency statically to the highest frequency supported by
64 config CPU_FREQ_DEFAULT_GOV_POWERSAVE
67 select CPU_FREQ_GOV_POWERSAVE
69 Use the CPUFreq governor 'powersave' as default. This sets
70 the frequency statically to the lowest frequency supported by
73 config CPU_FREQ_DEFAULT_GOV_USERSPACE
75 select CPU_FREQ_GOV_USERSPACE
77 Use the CPUFreq governor 'userspace' as default. This allows
78 you to set the CPU frequency manually or when a userspace
79 program shall be able to set the CPU dynamically without having
80 to enable the userspace governor manually.
82 config CPU_FREQ_DEFAULT_GOV_ONDEMAND
84 select CPU_FREQ_GOV_ONDEMAND
85 select CPU_FREQ_GOV_PERFORMANCE
87 Use the CPUFreq governor 'ondemand' as default. This allows
88 you to get a full dynamic frequency capable system by simply
89 loading your cpufreq low-level hardware driver.
90 Be aware that not all cpufreq drivers support the ondemand
91 governor. If unsure have a look at the help section of the
92 driver. Fallback governor will be the performance governor.
94 config CPU_FREQ_DEFAULT_GOV_CONSERVATIVE
96 select CPU_FREQ_GOV_CONSERVATIVE
97 select CPU_FREQ_GOV_PERFORMANCE
99 Use the CPUFreq governor 'conservative' as default. This allows
100 you to get a full dynamic frequency capable system by simply
101 loading your cpufreq low-level hardware driver.
102 Be aware that not all cpufreq drivers support the conservative
103 governor. If unsure have a look at the help section of the
104 driver. Fallback governor will be the performance governor.
107 config CPU_FREQ_GOV_PERFORMANCE
108 tristate "'performance' governor"
110 This cpufreq governor sets the frequency statically to the
111 highest available CPU frequency.
113 To compile this driver as a module, choose M here: the
114 module will be called cpufreq_performance.
118 config CPU_FREQ_GOV_POWERSAVE
119 tristate "'powersave' governor"
121 This cpufreq governor sets the frequency statically to the
122 lowest available CPU frequency.
124 To compile this driver as a module, choose M here: the
125 module will be called cpufreq_powersave.
129 config CPU_FREQ_GOV_USERSPACE
130 tristate "'userspace' governor for userspace frequency scaling"
132 Enable this cpufreq governor when you either want to set the
133 CPU frequency manually or when a userspace program shall
134 be able to set the CPU dynamically, like on LART
135 <http://www.lartmaker.nl/>.
137 To compile this driver as a module, choose M here: the
138 module will be called cpufreq_userspace.
140 For details, take a look at <file:Documentation/cpu-freq/>.
144 config CPU_FREQ_GOV_ONDEMAND
145 tristate "'ondemand' cpufreq policy governor"
146 select CPU_FREQ_TABLE
147 select CPU_FREQ_GOV_COMMON
149 'ondemand' - This driver adds a dynamic cpufreq policy governor.
150 The governor does a periodic polling and
151 changes frequency based on the CPU utilization.
152 The support for this governor depends on CPU capability to
153 do fast frequency switching (i.e, very low latency frequency
156 To compile this driver as a module, choose M here: the
157 module will be called cpufreq_ondemand.
159 For details, take a look at linux/Documentation/cpu-freq.
163 config CPU_FREQ_GOV_CONSERVATIVE
164 tristate "'conservative' cpufreq governor"
166 select CPU_FREQ_GOV_COMMON
168 'conservative' - this driver is rather similar to the 'ondemand'
169 governor both in its source code and its purpose, the difference is
170 its optimisation for better suitability in a battery powered
171 environment. The frequency is gracefully increased and decreased
172 rather than jumping to 100% when speed is required.
174 If you have a desktop machine then you should really be considering
175 the 'ondemand' governor instead, however if you are using a laptop,
176 PDA or even an AMD64 based computer (due to the unacceptable
177 step-by-step latency issues between the minimum and maximum frequency
178 transitions in the CPU) you will probably want to use this governor.
180 To compile this driver as a module, choose M here: the
181 module will be called cpufreq_conservative.
183 For details, take a look at linux/Documentation/cpu-freq.
187 config GENERIC_CPUFREQ_CPU0
188 tristate "Generic CPU0 cpufreq driver"
189 depends on HAVE_CLK && REGULATOR && PM_OPP && OF
190 select CPU_FREQ_TABLE
192 This adds a generic cpufreq driver for CPU0 frequency management.
193 It supports both uniprocessor (UP) and symmetric multiprocessor (SMP)
194 systems which share clock and voltage across all CPUs.
198 menu "x86 CPU frequency scaling drivers"
200 source "drivers/cpufreq/Kconfig.x86"
203 menu "ARM CPU frequency scaling drivers"
205 source "drivers/cpufreq/Kconfig.arm"
208 menu "PowerPC CPU frequency scaling drivers"
209 depends on PPC32 || PPC64
210 source "drivers/cpufreq/Kconfig.powerpc"